1. Field of the Invention
This invention broadly relates to a releasable, eccentric drive mechanism for reciprocating a sway bar used in harvesting and mowing equipment. More particularly, the drive mechanism of the present invention includes a wheel-like drive member such as a pulley that is supported for rotation about its central axis by a first shaft, and a second shaft connected to the drive member on an opposite side thereof and to the sway bar is disposed in offset relation to the first shaft for oscillation of the bar. The first and second shaft each present facing, inclined flat wall sections in wedging engagement with each other to retain the rotative position of the second shaft at a precise, pre-determined orientation relative to the first shaft and to the drive member in order to facilitate assembly and thereafter the mechanical strength of the interconnection and also, for example, to enable a flywheel connected to the second shaft remote from the drive pulley to be maintained in the proper, aligned relationship to the latter.
2. Description of the Prior Art
Certain types of mowers and harvesters are provided with a single or double sickle assembly which extends across the front of the implement for severing a crop as the implement is advanced across the field. Oftentimes, such sickles are reciprocated in a longitudinal direction by an oscillating sway bar which pivots adjacent the side of the implement about an upright axis. A source of rotary power is eccentrically coupled to the sway bar by an arangement of linkages for oscillation of the bar and thereby the sickle.
One example of a sickle drive mechanism is described in U.S. Pat. No. 3,941,003 dated Mar. 2, 1976 and assigned to the assignee of the present invention. The drive mechanism disclosed in U.S. Pat. No. 3,941,003 includes a drive shaft connected to a source of power, a semicircular weight fixed to the drive shaft, and a second shaft secured to the weight in offset or eccentric relationship to the drive shaft; in addition, the second shaft is coupled by means of a special linkage including a pair of pitman links to a sway bar for oscillation of the latter to effect a corresponding reciprocation of the sickle. In order to provide a better understanding of the subject matter of the present invention, the disclosure of the U.S. Pat. No. 3,941,003 is hereby expressly incorporated into the disclosure of the present document.
Recently, other types of drive mechanisms have been developed for sickle assemblies wherein the sway bar is coupled to a source of rotary power by means of a wheel-like drive member such as a pulley having a series of recesses for receiving a toothed belt. The pulley is supported for rotation about its central axis by a first shaft connected to a bearing, and a second shaft eccentrically mounted on the pulley in offset relationship to the first shaft is coupled by a set of linkages to the sway bar for timed oscillation of the latter. Optionally, a counterweight or flywheel may be secured to the second shaft remote from the pulley, and a third shaft coupled to the central axis of the counterweight in aligned, coaxial relationship with the first shaft cooperates with the first shaft to support of the drive member during rotation thereof.
Certain of the eccentric drive mechanisms known to those in the art are constructed by permanently fixing, as by welding, one shaft to another so that the longitudinal axes of the respective shafts are maintained in parallelism during operation of the machine. A counterweight, if used, is fixed in a desired, pre-selected rotative orientation relative to the second shaft so the counterweight is correctly positioned for dynamically balancing the rotative forces generated by other components of the drive mechanism including the drive pulley. Such construction, however, requires precise manual alignment of the shafts during assembly of the mechanism, and further prohibits ready disassembly when, for instance, maintenance is needed.
Hence, it would be a desirable advance in the art if an eccentric drive mechanism was provided having two, offset shafts connected to a wheel-like drive member in such a manner that both shafts can be released from the member without extensive labor or modification of the mechanism. Moreover, such a mechanism, when assembled, should provide a means for securing rigidly both of the shafts to the drive member in such a fashion that the rotative position of each shaft is maintained in a desired, preselected orientation.